1. Field of the Invention
This invention relates to adapter cards and more particularly relates to adapter card failover.
2. Description of the Related Art
A data processing system often includes a plurality of processor complexes. Each processor complex may include one or more microprocessors, cache memory, main memory, bridges to peripheral devices and buses, and the like. For example, a processor complex may communicate with a Peripheral Component Interconnect (PCI) bus through a north bridge and a south bridge. Adapter card peripheral devices such as network connections, storage devices, specialized compute engines, and the like may communicate with the processor complexes through the PCI bus.
Adapter cards typically comprise a plurality of semiconductor circuits mounted on a circuit board. An adapter card may connect to a bus through one or more connectors. Each adapter card may perform one or more specialized functions. For example, adapter cards may function as Ethernet controllers, Redundant Array of Independent Disks (RAID) controllers, and the like.
More than one processor complex of a data processing system may require access to an adapter card. For example, a cluster of two or more processor complexes may access a RAID controller adapter card in order to write data to and read data from hard disk drives in a fault-tolerant RAID subsystem. The adapter card communicating with two processor complexes may be referred to as a twin-tailed adapter card.
Although multiple processor complexes may access the adapter card, one processor complex controls the adapter card in terms of configuration and failure recovery. The processor complex controlling the adapter card is referred to herein as an owner processor complex. The owner processor complex may configure and manage the adapter card. Providing a single owner processor complex may prevent two or more processor complexes from attempting to configure and manage the adapter card.
Unfortunately, if the owner processor complex fails, other processor complexes may be unable to use the adapter card. As a result, the function of the data processor system may be degraded and/or impaired.